This invention relates to a computer system which has remote copying technology, and more specifically to a technique of monitoring a failure in a computer system.
In recent years, computer systems of late handle larger size data and more frequent data update than ever. How to backup such data is one of important matters in storage technology, along with how quickly a computer system can recover from a failure to resume normal operation. Remote copy is one solution in which plural storage subsystems (external storage systems) having magnetic disk arrays are set up in remote sites and connected by communication paths and data updated in one of the storage subsystems is automatically copied to the other storage subsystems without the help of a host computer (refer to JP 2004-13367 A).
Another solution proposed is a failure checking method which uses a system composed of a first host group; a second host group linked via a network to the first host group; and a remote mirror that is incorporated in the first host group and the second host group and that is composed of a first site heartbeat storage volume and a second site heartbeat storage volume linked via a remote link to the first site heartbeat storage volume, and in which the first host group creates a heartbeat signal and uses the network or the remote mirror, or both, to sent the heartbeat signal to the second host group, and the second host takes over operation of the system upon receiving an incorrect heartbeat signal from the first host group (refer to JP 2002-312189 A).
Also proposed is a technique in which a first storage subsystem connected to a host computer via a communication path receives, from the host computer, a control command for a volume pair in another storage subsystem and transfers the control command to the corresponding storage subsystem, which sends a response to the control command to the host computer via the first storage subsystem. The technique enables the host computer to receive a response from a remote-level storage subsystem which is not connected directly to the host computer via a communication path (refer to U.S. Pat. No. 6,529,944 B).